Exploring high hydrostatic pressure environments such as deep sea presents significant challenges to robotic devices, for they often rely on strong yet heavy and costly protective structures to shield components from being crushed by the extreme pressure. To dismiss the need for bulky protection shells for actuation devices, we reported an extreme-hydrostatic-pressure resilient rotary dielectric elastomer actuator (DEA) for propulsion application in deep-sea pressure condition. DEAs are inherently resistant to damage caused by external pressure, due to their uniform and cavity-free structure. In this study, we analyzed the material properties of the DEA’s elastomer, evaluated the rotary actuator’s lifespan at up to 110 MPa high-pressure liquid conditions, and output performance under both ambient and 30 MPa (equivalent to 3,000 m underwater). Our results show that the rotary actuator maintained functionality at such hydrostatic pressure, with a lifespan exceeding 300,000 cycles and a high rotational output speed of 820 rpm. The rotary actuator was subsequently used to drive the robot with a propeller in a simulated deep-sea pressure fluidic environment, demonstrating our DEA’s performance as well as design simplicity for deep-sea applications without protection structures. While high hydrostatic pressure negatively impacted the actuator’s lifespan and slightly reduced its dynamic performance, our results confirmed that the DEA was a viable solution for deep-sea exploration, laying a solid foundation for the further development of DEA-powered devices for underwater missions.

The development of high-performance bionic legged robots can benefit from the continued advancements in various actuation methods, such as artificial muscles. This work presents a musculoskeletal bionic leg driven by fluidic elastomer actuators (FEAs), showcasing their potential as artificial muscles for legged robots. Our approach integrates three key innovations: First, we established a mechanics model using thin plate theory to optimize the bellows shell structure of the FEAs, achieving high force output while maintaining inherent compliance. Second, we developed a lightweight embedded optoelectronic sensing system that enables closed-loop control without significantly increasing mass. Third, we designed a two-joint leg in the sagittal plane that utilizes a bionic configuration incorporating both monoarticular and biarticular FEAs. The leg demonstrated robust performance across various tasks including extreme positional movements, load-bearing squats supporting up to 2.45 times its body weight, vertical jumping with 147 mm ground clearance, and stable walking. Notably, our embedded sensing system successfully detected ground contact states without additional foot sensors, enabling reliable gait control while minimizing complexity and weight. The experimental results validate both the mechanical capabilities of the optimized FEAs and their controllability through embedded sensing, laying a foundation for developing full legged robots with muscle-like actuation.

Recently, various soft universal grippers have been developed due to their reduced control complexity and satisfying grasping capability. The gripping range of a gripper plays a key role in its universality. This article presents a pneumatically actuated soft-rigid hybrid multifinger gripper that has a wide gripping range by adjusting its initial grasp postures. The gripper is compact (dimensions:$\text{100} \times \text{60} \times \text{170}$mm), lightweight (weight: 380 g), and modular. It consists of four modules, with each module containing three pneumatic actuators (a distance-adjusting actuator, an angle-adjusting actuator, and a finger actuator) and rigid connectors. Through initial grasp posture adjustment, and fingers with tapered angles to generate nonconstant bending while grasping, the gripper can grasp objects of a wide variety of sizes and weights, thus increasing its universality. The gripper is tested to characterize its distance adjustment range, angle adjustment range, and stiffnesses in load-bearing directions, at continuously changing pneumatic pressures. The distance adjustment range and angle adjustment range of the gripper are 0–64.4 mm (64.4% of the initial gripper length) and 0$^{\circ}$–140$^{\circ}$, respectively. The maximum stiffnesses of distance-adjusting actuator and angle-adjusting actuator are 3331 and 1.15 N$\cdot$m/rad, respectively. Finally, grasping experiments show that our gripper can successfully grasp objects with diameters ranging from 0.5 to 180 mm, lengths ranging from 10 to 325 mm, and the heaviest object it can grasp is 2.1 kg (more than five folds of its own weight). The results demonstrated that our pneumatic gripper has an increased gripping range without adding other types of energy sources and its enhanced universality will expedite various applications in daily life and industry.